mollify vs tone down

mollify

verb
  • To soften; to make tender 

  • To ease a burden, particularly worry; make less painful; to comfort. 

  • To appease (anger), pacify, gain the good will of. 

tone down

verb
  • To moderate or relax; to diminish or weaken the striking characteristics of; to soften. 

  • To make a television program, piece of writing, etc. less offensive and so more suitable for a family audience. 

  • To relax; to make quieter or less obtrusive; to make milder. 

How often have the words mollify and tone down occurred in a corpus of books? (source: Google Ngram Viewer )